1. Technical Field of the Invention
This invention relates to a structure for mounting and to a water pump for a water-cooled internal combustion engine. More particularly, this invention relates to a structure for mounting and removing a water pump to and from a water-cooled internal combustion engine which may be installed on a small-sized vehicle such as a motorcycle. The invention also relates to a cooling system incorporating the inventive water pump.
2. Description of Related Art
Conventional water-cooled internal combustion engines for small-sized vehicles, such as Japanese Utility Model Laid-Open No. Sho 62-179323 that is illustrated in FIGS. 7 to 9, mount the water pump 03 to a pump fixing wall 04 that is formed at a right side wall of an upper cylinder block fixing part 02 of a crank case 01. A pump housing 05 for the water pump 03 is removably fixed to an outside part of the pump fixing wall 04.
In addition, the pump drive shaft 06 is rotatably mounted to the pump fixing wall 04 and a pump rotor 07 is removably installed at an outer end of the pump drive shaft 06. Further, a driven sprocket 08 is removably installed on an inner end of the pump drive shaft 06.
Further, an intermediate shaft 010 is arranged at an intermediate location between crank shaft 09 and the pump drive shaft 06. An inner end of the intermediate shaft 010 is rotationally mounted to the crank case 01 and an outer end of the intermediate shaft 010 is rotatably mounted to supporting member 011 which is removably fixed to the crank case 01.
The drive sprocket 012 and the driven sprocket 013 are integrally fitted to an inner side and an outer side of the intermediate shaft 010, respectively.
Further, an crank shaft output gear 014 is integrally fitted to the crank shaft 09 at an intermediate position axially between the drive sprocket 012 and a driven sprocket 013 of the intermediate shaft 010. A crank shaft drive sprocket 015 is integrally fitted to the crank shaft 09 and located outboard with respect to the crank shaft output gear 014.
A first chain 016 transmits power from the crank shaft drive sprocket 015 to the driven sprocket 013 of the intermediate shaft 010. A second chain 017 transmits power from the drive sprocket 012 of the intermediate shaft 010 to the driven sprocket 08 of the pump drive shaft 06. In this way, the crankshaft 09 drives the pump drive shaft 06 which, in turn, rotates the pump rotor 07.
In the conventional water-cooled internal combustion engine illustrated in FIGS. 7 to 9 and described above, the pump drive shaft 06 is rotatably mounted to the pump fixing wall 04 which is integral with the upper cylinder block fixing part 02. Furthermore, the driven sprocket 08 is installed inside the pump housing 05 and inside of the upper cylinder block fixing part 02.
With this conventional structure, even if the pump housing 05 is removed from the pump fixing wall 04, the pump drive shaft 06 and the pump rotor 07 could not be easily removed. The result is that removing the pump drive shaft 06 and the pump rotor 07 (which is necessary to replace the water pump) is impossible so long as the upper cylinder block fixing part 02 that is integral with the crank case 01 is not removed from the cylinder block (not shown) and so long as the driven sprocket 08 was not removed from the pump drive shaft 06. In other words, the conventional water pump structure 03 dictates disassembly of the driven sprocket 08, upper cylinder block fixing part 02, and crank case 01 to remove the pump drive shaft 06 and the pump rotor 07 and, eventually, the water pump 03.
Further complicating this disassembly procedure is that there is only a narrow space in the crank case 01 in which to disassemble and remove the driven sprocket 08 from the pump drive shaft 06. Assembling the conventional water pump 03 is also quite difficult and cumbersome for the same reasons.
Furthermore, maintenance and inspection of the water pump 03 could not easily be performed with the conventional structure.